通过平均的聚合的可靠性
Dependability in Aggregation by Averaging
摘要：
聚合是现代分布式应用程序的重要构建块，允许确定有意义的属性（例如网络大小，总存储容量，平均负载，多数等）。用于指导系统的执行。然而，大多数现有的聚合算法表现出相关的可靠性问题时，在实际应用环境中使用的前景。本文揭示了基于迭代平均技术的聚集算法的一些可靠性问题，并给出了解决这些问题的一些方向。这类算法被认为是鲁棒的（当与常见的基于树的方法相比时），独立于所使用的路由拓扑，并在所有节点处提供聚合结果。然而，他们的鲁棒性受到强烈的挑战，他们的正确性往往妥协，当改变他们的工作环境的假设，以更现实的。这类算法的正确性依赖于基本不变式的维持，通常称为“质量守恒”。我们将认为，这个主要的不变量在实际设置中经常被打破，并且需要额外的机制和修改来维护它，从而导致算法性能的一些下降。特别是，我们讨论了三个代表性的算法Push-Sum协议，Push-Pull Gossip协议和分布式随机路由协议在异步和故障（消息丢失和节点崩溃）环境下的行为。更具体地说，我们提出并评估两个新版本的推拉八卦协议，解决其消息交织问题（即使在同步操作模式下证明）。
英文摘要：
Aggregation is an important building block of modern distributed applications, allowing the determination of meaningful properties (e.g. network size, total storage capacity, average load, majorities, etc.) that are used to direct the execution of the system. However, the majority of the existing aggregation algorithms exhibit relevant dependability issues, when prospecting their use in real application environments. In this paper, we reveal some dependability issues of aggregation algorithms based on iterative averaging techniques, giving some directions to solve them. This class of algorithms is considered robust (when compared to common tree-based approaches), being independent from the used routing topology and providing an aggregation result at all nodes. However, their robustness is strongly challenged and their correctness often compromised, when changing the assumptions of their working environment to more realistic ones. The correctness of this class of algorithms relies on the maintenance of a fundamental invariant, commonly designated as "mass conservation". We will argue that this main invariant is often broken in practical settings, and that additional mechanisms and modifications are required to maintain it, incurring in some degradation of the algorithms performance. In particular, we discuss the behavior of three representative algorithms Push-Sum Protocol, Push-Pull Gossip protocol and Distributed Random Grouping under asynchronous and faulty (with message loss and node crashes) environments. More specifically, we propose and evaluate two new versions of the Push-Pull Gossip protocol, which solve its message interleaving problem (evidenced even in a synchronous operation mode).
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
